When constant direct current(DC) is impressed on DC deep well grounding electrode, electrochemical, corrosion reaction occurs between the well cementing concrete and the steel tube, and the well cementing concrete acts as electrolyte. The reaction leads to the electrical resistivity variation of the well cementing concrete. In order to study the electrical resistivity variation law of well cementing concrete in different conditions with the DC duration, experiments are carried out in this paper. According to the water cement ratio of the practical deep well grounding electrode engineering, the concrete samples are prepared. The DC experiments for concrete samples which are cured for 3~7 days and entirely cured are conducted. The results show that the concrete electrical resistivity conforms to Archie formula at the beginning of curing period, the concrete electrical resistivity during curing period increases with the DC duration and so does the entirely cured and impregnated concrete, while the electrical resistivity of entirely cured and dried concrete decreases with the DC duration. The analysis shows that DC polarization is the main reason leading to the difference of the two trends.